Dependence of scintillation characteristics in the CsI(Tl) crystal on Tl* concentrations under electron and alpha particles excitations

This paper reports the emission spectra, pulse heights and decay curves of CsI(Tl) crystals with a Tl* concentration ranging from 10^-6 mol to 10^-2 mol, under electron and alpha particle excitations. Larger pulse heights from the crystals with Tl+concentration of more than 10^-3 mol were observed for a higher ionization density of alpha particle excitation, compared with those of electron excitation. This enhancement may be explained in terms of the higher. Scintillation efficiency for higher Tl* concentration. Decay curves under electron and alpha particle excitations were compared with the decay curve under pulsed UV excitation. The observed decay curves were explained in terms of the sum of the three energy transfer processes to create excited states (Tl⁺)*; the prompt process, the V_k diffusion process to Tl⁰ and the electron release process from Tl⁰ to Tl⁺⁺. Here, Tl⁰ and Tl⁺⁺ were-produced through (Tl⁺⁺ electron)→Tl⁰ and (Tl⁺⁺ hole (or V_k)) →Tl⁺⁺